JP2002203777A - Electron beam image drawing method and system thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform electron beam image drawing at a high speed while increase of Coulomb's effect is prevented. SOLUTION: Electron beam image drawing devices 111, 121 and 131 which have different features are combined. Pattern data for performing image drawing are divided into a part for performing image drawing by a variable shaping system, and a part for performing image drawing by a collective figure system by using a data dividing device 102, and two pattern data are formed. Pattern data in the part for performing image drawing by the variable shaping system are assigned to an electron beam image drawing device whose luminance is high, and data in the part for performing image drawing by the collective figure system are assigned to an electron beam image drawing device whose luminance is low. One specimen to be image-drawn is subjected to image drawing by the two devices, independently.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam drawing method and an electron beam drawing system used for processing and drawing semiconductor integrated circuits and photomasks for semiconductor circuit devices.

[0002]

2. Description of the Related Art With the increase in density and integration of semiconductor circuits typified by LSIs, miniaturization of circuit patterns to be formed is rapidly progressing. Electron beam lithography is an effective means for forming fine patterns, but higher throughput is required for application to production sites.

Most electron beam writing apparatuses use a so-called variable shaping method for forming a variable rectangular beam.
However, as circuit patterns have become finer and the number of patterns per sample has increased and higher throughput has been demanded, a group of aperture stops with specific functions has been created using the area beam of the variable shaping method. A collective figure method has been developed that irradiates and draws with a patterned electron beam. Also, as described in Japanese Patent Application Laid-Open No. 10-199796, a method of enlarging the opening of a collective figure and performing scanning by drawing over the opening, or moving the collective opening as described in Japanese Patent No. 30342285. However, there has also been proposed a method of performing writing by synchronizing this with the beam deflection and the sample stage. Japanese Patent Application Laid-Open No. 5-251317 and Japanese Journal of Applied
Physics (Jpn. J. Appl. Phys.), Volume 34 (19
1995, p. 6658, a method has been proposed in which, similarly to optical transfer, an aperture-type or scattering-type mask of a semiconductor integrated circuit full chip is prepared and transfer is performed with a beam having a relatively large area. In all of these methods, a mask image is projected onto a sample by an electron lens and writing is performed while positioning the image with a deflector.
These are collectively referred to as a collective figure system.

[0004]

The main factors that determine the throughput of the above-described electron beam lithography apparatus are as follows.
This is the current value of the electron beam irradiating (one shot) on the sample at a time. When the beam current value is increased, there is a problem that the pattern shape formed due to the beam blur due to the Coulomb effect deteriorates. Therefore, if the current density obtained by dividing the beam current value by the beam area is increased, the variable shaping method in which writing is performed with a small beam area is good, but in the collective figure method in which a relatively large area is transferred, the current value becomes large and the pattern shape becomes large. Will deteriorate. On the other hand, when the current density is lowered, the drawing time in the variable shaping method becomes longer.

To solve this problem, see, for example, Japanese Patent Laid-Open No. 11-2
As described in Japanese Patent No. 19879, when writing one sample, the current density is set so that the beam area is small and the current density is high in the variable shaping method, and the beam area is relatively large and the current density is small in the batch pattern method. Is switched to perform drawing with the maximum current value within the range allowed by the Coulomb effect, the drawing speed is improved. However, in this example, since a condenser lens is used as a means for changing the current density, the beam opening angle changes at the same time as the current density changes. Beam blur due to the Coulomb effect is roughly proportional to the current value and inversely proportional to the opening angle. In this case, the current density is proportional to the square of the opening angle. Therefore, even if the current density is reduced to 1/2 by the condenser lens under a constant current amount, the opening angle becomes 1/2 and the Coulomb effect increases.

An object of the present invention is to perform electron beam writing at high speed while preventing an increase in the Coulomb effect. Another object of the present invention is to provide an electron beam writing method for effectively using different combinations and an electron beam writing system capable of realizing the method.

[0007]

In order to achieve the above object, in the present invention, electron beam writing is performed at high speed by combining electron beam writing apparatuses having different writing methods and current densities. First, pattern data to be drawn is divided by a data dividing device into a part to be drawn by a variable shaping method and a part to be drawn by a collective figure method.
Create two pattern data. Next, the pattern data of a portion to be drawn by variable shaping is assigned to an electron beam writing device having a high brightness, and the portion to be drawn by the collective graphic method is assigned to an electron beam writing device having a low brightness. By separately writing one sample to be written with these two devices, writing can be performed with an optimum current density, and high-speed writing can be performed. Brightness is the amount of current per unit area unit solid angle. Therefore, by changing the brightness, it is possible to change the current density without changing the opening angle,
It is possible to keep the Coulomb effect unchanged under a constant current amount.

The number of divisions of the pattern data is not limited to two. Depending on the drawing time difference between the two devices and the size of the collective figure, the pattern data is further divided, and each pattern data is separated into another. What is necessary is just to allocate to a drawing apparatus and to perform drawing.

That is, in the electron beam writing method according to the present invention, in an electron beam writing method for irradiating a sample with an electron beam to write a pattern, writing is performed on one sample using a plurality of electron optical systems having different luminances. It is characterized by the following.

The plurality of electron optical systems include an electron optical system that performs pattern drawing by a variable shaping method, an electron optical system that performs pattern drawing by a collective figure system, and an electron optical system that performs large area pattern drawing by a transfer method. It can be a combination of two or more. These electron optical systems may be incorporated in one electron beam lithography apparatus, or each may constitute a separate electron beam lithography apparatus.

An electron beam writing method according to the present invention is also directed to an electron beam writing method for irradiating a sample with an electron beam to write a pattern. The step of dividing into the part to be drawn by the pattern forming part, the part to be drawn by the variable forming method is drawn by an electron optical system that draws a pattern by the variable forming method, and the part to be drawn by the collective figure method is patterned A step of drawing by an electron optical system for drawing, wherein the brightness of the electron optical system for drawing a pattern by the variable shaping method is higher than the brightness of the electron optical system for drawing a pattern by the collective figure method.

When dividing the pattern data, the portion to be drawn by the collective figure method may be further divided according to the type or area of the collective figure. Further, the pattern data of the method in which the drawing time of the portion for performing the drawing by the variable shaping method and the drawing time of the portion to be drawn by the collective graphic method are long based on the calculated drawing time may be further divided.

According to the electron beam writing method of the present invention, in the electron beam writing method of writing a pattern on a sample by using both the variable shaping method and the collective graphic method, pattern data to be written is drawn by the variable shaping method. A step of dividing into a part and a part to be drawn by a collective graphic method, a step of calculating a drawing time of the divided pattern data, and an electron optical system for performing pattern drawing by a variable shaping method based on the calculated drawing time. A step of adjusting the brightness of an electron optical system that performs pattern drawing by the collective figure method, and drawing on one sample by an electron optical system that performs pattern drawing by the variable shaping method and an electron optical system that performs pattern drawing by the collective figure method And a step.

An electron beam writing system according to the present invention comprises:
An electron beam lithography system that includes an electron optical system that performs pattern drawing by a variable shaping method and an electron optical system that performs pattern drawing by a batch figure method. Pattern dividing means for dividing into a portion to be drawn by a graphic method, drawing time calculating means for calculating a drawing time of the divided pattern data, and electro-optical for performing pattern drawing by a variable shaping method based on the calculated drawing time Means for adjusting the brightness of the system and the brightness of the electron optical system that performs pattern drawing in the collective figure system, and between the electron optical system that performs pattern drawing in the variable shaping method and the electron optical system that performs pattern drawing in the collective figure system An electron optical system that includes a sample conveying unit that conveys a sample and performs pattern drawing by a variable molding method; and an electron optical system that performs pattern drawing by a collective graphic method. And performing drawing on a single sample using.

An electron beam writing system according to the present invention comprises:
An electron beam writing system including an electron optical system for performing pattern writing by a variable shaping method and an electron optical system for performing pattern writing by a collective figure method, wherein an irradiation amount for correcting a proximity effect of pattern data to be written. Means for performing a correction operation, pattern division means for dividing the pattern data subjected to the irradiation amount correction operation into a part for drawing by the variable shaping method and a part for drawing by the collective figure method, and a drawing time for the divided pattern data Means for adjusting the brightness of the electron optical system for performing pattern drawing by the variable shaping method based on the calculated drawing time and the brightness of the electron optical system for performing pattern drawing by the collective figure method, Sample transport means for transporting a sample is provided between an electron optical system that performs pattern drawing by a molding method and an electron optical system that performs pattern drawing by a collective graphic method. And performing proximity effect correction to draw on a single sample using an electron optical system for performing pattern writing in bulk graphic manner the electron optical system for performing pattern drawn with variable shaping method.

An electron optical system for performing pattern drawing by the variable shaping method of the electron beam drawing system and an electron optical system for performing pattern drawing by the collective figure method may be incorporated in one electron beam drawing apparatus. May constitute a separate electron beam writing apparatus.

Preferably, in the electron beam writing system, a plurality of electron beam writing apparatuses are connected in a vacuum chamber, and the sample transfer means moves in the vacuum chamber to transfer the sample to the electron beam writing apparatus. . Also, the sample transport means is
When the sample is transported into the electron beam writing apparatus while being mounted on the sample holding means, and writing is performed while being mounted on the sample holding means, the overlay error can be reduced.

It is preferable to use an optical alignment mark detection device when drawing the divided pattern data on one sample by using a plurality of electron optical systems. In addition, it is preferable that each of the combined drawing algorithms when the combined pattern writing is performed on one sample by using a plurality of electron optical systems, is the same. The electron beam writing method or the electron beam writing system of the present invention can be used for pattern writing of a semiconductor circuit device or a photomask for a semiconductor circuit device.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. First, the configuration of the electron beam writing apparatus used in the present invention will be described. FIG. 14 shows an example of an electron beam writing apparatus of the collective figure system. The example shown here is an apparatus which can also perform drawing by a variable shaping method using a variable shaping beam method that can change the size of a rectangular beam in a portion other than a collective figure.

An electron beam 1202 emitted from an electron gun 1201 is irradiated on a first mask 1203 having a rectangular opening, and is further imaged on a second mask 1205. The image of the second mask 1205 is projected and deflected by the reduction lens 1206 and the objective deflecting lens 1207, and is projected on the sample 1208 coated with the photosensitive agent to perform drawing. This part is the electron optical system. At this time, a plurality of pattern-shaped openings provided in advance in the second mask 1205 are selected by the selection deflector 1204. The XY stage controller 1213 moves the sample 1208 placed on the XY stage 1209 for drawing, except for the area that can be deflected by the objective deflecting lens 1207. The entire drawing is uniformly controlled by the drawing control device 1210 according to the drawing pattern data. The movement of the second mask 1205 is performed by the mask moving mechanism 1211, and is controlled by the moving mechanism control device 1212 according to the drawing pattern. Writing can be performed while moving the second mask 1205. Further, the second mask 1205 and the XY stage 1 are formed by using an opening larger than the size of the electron beam irradiated onto the second mask 1205.
There is also a method in which drawing is performed by synchronously moving the image with the image 209.

FIG. 15 illustrates a top view of the second mask 1205. On the second mask 1205, a collective figure opening 1301 is arranged around the variable shaping opening 1302. In this example, five batch figure openings 1301 can be selected by the selection deflector.

FIG. 16 shows an example of a transfer type electron beam writing apparatus. An electron beam 1402 generated by an illumination system 1401 including an electron source, an acceleration space, and a lens is partially irradiated on a mask 1405 by a lens 1403 and a deflector 1404. The mask 1405 includes two types, a scattering type in which a pattern is formed on a silicon thin film or the like with a material having a large atomic number, and an opening type in which holes are formed in the silicon thin film. In each case, the contrast is provided by the difference in scattering between the pattern portion and the non-pattern portion.
The beam that has passed or scattered through the mask 1405 is deflector 1
At 407, only the beam incident on the first projection lens 1406 and scattered is cut by the limiting aperture 1408. The beam passing through the restriction aperture 1408 is
It is positioned by the projection lens 1409 and the deflector 1410 and projected onto the sample 1411. The first projection lens 1406 and the second projection lens 1409 have a doublet configuration, and the projection magnification is determined by the ratio of the focal length of the two lenses. For example, a 1 mm square pattern is reduced to 1/4 on the mask 1405 and projected on a sample at 250 μm square. This configuration can project with less aberration such as distortion and blur. The beam position on the mask 1405 is determined by the deflector 140
The sample 141 moves mechanically at the same time that the sample 141 is deflected.
The drawing is performed in synchronization with a stage (not shown) on which 1 is mounted.

In the above two drawing apparatuses, a function of irradiating a mask with an electron beam, projecting a mask image on a sample, and performing writing while determining the position of the electron beam with a deflector and a sample stage. And the configuration is the same. Therefore, in the present specification, these are collectively referred to as a collective graphic system.

Hereinafter, the present invention will be described in detail with reference to the drawings. [First Embodiment] FIG. 1 is a system configuration diagram showing an example of an electron beam writing system according to the present invention. The electron beam writing apparatuses 111, 121 and 131 are the same type of electron beam writing apparatus as shown in FIG. The pattern data 103 to be drawn is divided by the data dividing device 102 into variable shaping data and collective figure data. Then, the data is sent to control devices 112, 122, and 132 that control the electron beam drawing devices 111, 121, and 131, respectively. The sample to be written is supplied to the electron beam writing devices 111 and 12 by the sample transfer device 101 operating in the vacuum chamber 106.
1 and 131, and drawing is performed according to the divided pattern data. The drawing operation is the same as that shown in FIG.

The drawing time of each of the divided pattern data is calculated by the drawing time calculation device 105. The drawing time can be determined by multiplying the sum of the shot residence time and the beam deflection waiting time determined by the sensitivity of the photosensitive agent of the sample and the current density by the number of shots, and further adding the overall overhead time. Here, for example, it is assumed that the drawing time of the collective figure portion is about twice as long as the drawing time of the variable shaping portion. In this case, it is most efficient if the electron beam drawing apparatus 111 draws the variable shaping section and the electron beam drawing apparatuses 121 and 131 draw the batch figure section. Further, the brightness of each electron optical system may be determined so that the current density becomes an integral multiple (here, twice).

FIG. 2 shows the drawing order. First, sample 1 is placed in apparatus 111, sample 2 is placed in apparatus 121, and sample 3 is placed in apparatus 13
1 is loaded. Since the drawing of the sample 1 by the electron beam drawing apparatus 111 for drawing the variable shaping unit is completed in half the time of the other apparatus, after the drawing of the sample 1 is completed, the sample 1 is retracted and the drawing of the sample 4 is started. Next, after the drawing by each device is completed, the sample 1 is transferred to the device 121 and the sample 2 is transferred to the device 1.
11, the sample 3 is retracted, and the sample 4 is moved to the device 131. After the writing by the electron beam writing apparatus 111, the writing of the sample 2 is completed. Subsequently, the sample 3 is loaded into the apparatus 111 and writing is started. The writing of the samples 3, 4, and 1 is completed almost simultaneously, and the writing of all the four samples is completed. Thereafter, this procedure is similarly repeated. These procedures are controlled by the drawing procedure control device 104 based on the drawing time obtained by the drawing time calculation device 105.

FIG. 3 shows an example of a pattern to be drawn. The upper portion of the drawing pattern 31 which is a repetitive pattern is a portion to be drawn in a collective figure, and the lower portion is a portion to be drawn by variable shaping. The drawing pattern 31 is divided to generate a pattern of a collective figure pattern 32 and a variable shaping pattern 33. The variable shaping pattern 33 divided by the data dividing device 102 shown in FIG. 1 is sent to the control device 112, and the collective figure pattern 32 is sent to the control devices 122 and 132.

Next, both types of current densities will be described.
For example, the size of a pattern to be drawn by an electron beam drawing system is about 0.1 μm. On the other hand, the size of a collective figure is, for example, 5 μm square, and is usually several tens%.
There are many patterns that have an aperture through which the beam passes. Here, assuming that the current density is the amount of current per unit area, the beam current of a collective figure is 10 times or more as large as that of variable shaping at the same current density.

On the other hand, the beam blur due to the Coulomb effect is
If the specifications of the electron optical system are the same, the value increases almost in proportion to the beam current value. Therefore, if the beam current of the collective figure is limited by the beam blur due to the Coulomb effect, the current density in the variable shaping is reduced, and if the same beam blur as the collective figure is allowed, the current density can be increased. In the conventional drawing method, switching between the variable shaping unit and the collective figure unit must be performed at a high speed of about the beam deflection waiting time, and it is practically difficult to realize an electron optical system that switches the current density at this speed. . Therefore, for example, if the current density of the electron optical system for drawing a batch figure is set to 5 A / cm ² and the current density of the electron optical system for writing a variable shape is set to 40 A / cm ² , writing can be performed efficiently. It is possible to do. For example, in the pattern of FIG. 3, if the variable shaping is 38 shots and the collective figure is 9 shots, and the current density of the variable shaping type electron optical system is set to eight times the current density of the collective figure type electron optical system, The drawing time of the variable shaping drawing is about 1/2 that of the batch figure drawing.

There are several methods for changing the current density. For example, by using a condenser lens as described in the prior art, the angle of view of the electron gun can be changed without changing the crossover position. However, in this method, since the luminance does not change, the beam opening angle changes at the same time as the current density. Beam blur due to the Coulomb effect is roughly proportional to the current value and inversely proportional to the opening angle. On the other hand, the current value is proportional to the square of the opening angle. For example, when the current density of 40 A / cm ² at the opening angle of 5 mrad is reduced to 1/4 by the condenser lens, the opening angle is reduced to 1/2 of 2.5 mrad to reduce the current density to 1/4. There is a need. However, since the Coulomb effect is inversely proportional to the opening angle, if the same current is used in the variable shaping method and the collective figure method, the beam blur will be twice that in the case of a current density of 40 A / cm ² . Therefore, this method does not solve the beam blur due to the Coulomb effect.

On the other hand, if the brightness of the electron gun is increased, the current density can be increased without changing the opening angle. As a method of increasing the brightness, there is a method of changing the electron source itself. However, in the case of a thermionic source such as LaB ₆ , it is a simple method to change the heating conditions or to change the voltage of an electrode (Wehnelt) that suppresses the generation of thermoelectrons. Also,
There are also a method of controlling the electron gun by adding an electrode having a lens function, and a method of superposing a magnetic lens on the electron gun.
For example, when a LaB6 thermoelectron gun is used, an opening angle of 5
The luminance to achieve a current density of 40 A / cm ² at mrad is 5 × 10
It is about ⁵ A / cm ² str. Since the current density is proportional to the luminance, if the heating temperature is set to 6.25 × 10 ⁴ A / cm ² str by lowering the heating temperature or increasing the Wehnelt voltage, the current density becomes 5 A / cm ² . In this embodiment, the luminance was changed by increasing the Wehnelt voltage. At this time, since the opening angle did not change, even if the same current was used in the variable shaping method and the batch figure method, the beam blur due to the Coulomb effect did not change, and as a result, the same beam current value could be used.

In the above example, the drawing time of the variable shaping method is short, but the drawing time of the variable shaping method may be long depending on the pattern to be drawn. In this case, the electron beam drawing apparatuses 111 and 121 may draw the variable shaping section, and the electron beam drawing apparatus 131 may draw the batch figure section.

Electron beam writing must be performed in a vacuum in order to use an electron beam. Usually, before drawing, the sample is evacuated in a chamber different from the sample stage and then loaded on the sample stage. When drawing is performed continuously between a plurality of apparatuses, it is wasteful to exhaust and evacuate each time. Therefore, if the apparatuses are connected to each other in a vacuum chamber and the sample is moved in the vacuum chamber, the waste time is eliminated. In FIG. 1, a portion surrounded by a broken line is a vacuum chamber 106.
The sample transfer device 101 operates in the vacuum chamber 106. If the sample transport device can handle a plurality of samples at one time, the efficiency of sample exchange will be improved.

FIG. 4 shows an example of a mounting form of the apparatus. In this example, three electron beam writing apparatuses 41, 4
A sample transfer device 44 that operates in a vacuum is installed at the center between 2 and 43. The sample can be exchanged between the sample transport device 44 and the three sample stages. At this time, if there are a plurality of arms of the sample transport device 44, the sample can be efficiently exchanged. The sample transfer device exchanges samples with the vacuum exhaust chamber 45 to exchange samples with the sample cassette 46 in the atmosphere. The vacuum pumping chamber 45 is most efficient if the same number of samples (three in this case) as the number of electron beam drawing apparatuses can be simultaneously evacuated and atmosphericized.

When writing the same sample with a plurality of writing devices, the overlay accuracy is important. One of the factors of the overlay error is a sample holding form. When a sample is mounted on a sample holding device, an overlay error may increase due to warpage or distortion of the sample. In order to avoid such errors, the writing is performed by moving the sample holding device 51 shown in FIG. 5 between a plurality of writing devices. FIG. 5 (a)
FIG. 5 shows an example of a sample holding device 51 on which a wafer 52 is mounted.
(B) shows a sample holding device 51 on which a glass mask 53 is mounted.
Here is an example.

When performing electron beam writing, the CAD data for LSI design is converted into data for an electron beam writing apparatus and sent to the control unit of the electron beam writing apparatus. Drawing is performed by controlling a deflector and the like. At the time of data conversion, for a part to be drawn with a collective figure, the pattern data of that part is deleted and replaced with a code indicating a collective pattern.

The operation of the pattern data dividing device will be described with reference to FIG. The pattern data 61 for electron beam drawing usually stores a drawing condition section 62 describing the size and number of the entire pattern, the minimum drawing unit, and the like, the size and coordinates of each pattern, a code indicating a collective figure, and the like. And a pattern data section 63. The pattern data 61 is read, and the variable shaping pattern data 66 composed of the drawing condition part 62 and the variable shaping data part 64, the drawing condition part 62 and the collective figure data part 65
Is divided into the collective figure pattern data 67 composed of

FIG. 7 shows a processing flow of pattern data division. Read the pattern data 61 (step 1
1) Since the drawing condition unit 62 is common, the drawing condition unit 62 is output to the variable shaping pattern data 66 and the collective figure pattern data 67, respectively (step 12). Next, the type of data included in the pattern data section 63 is determined (step 13), the variable shaping data is output to the variable shaping pattern data 66 (step 14), and the collective graphic data is output to the collective graphic pattern data 67. (Step 15). In step 16, the presence or absence of remaining data is determined,
Step 13 until output of all pattern data is completed
And the process of step 16 is repeated. As a result, two pattern data are created. At this time, it is assumed that the mask of the collective figure is prepared in advance. The batch figure data of the unprepared mask is output as variable shaping data. This data division may be performed by software or hardware.

[Second Embodiment] In the drawing method described in the first embodiment, when drawing by the collective figure method, in general, the larger the area of the collective figure that can be drawn by one irradiation is, the more patterns are formed. The drawing speed increases due to the capture. However, in order to transfer large areas with less distortion and blur, the number of components of the electron optical system such as deflectors is increased,
Complicated control must be performed. For this reason, for example, the details of the electron optical system that draws a 5 μm square collective figure and a 250 μm square collective figure on a sample are different. On the other hand, since the area of the collective figure is large, the beam blur due to the Coulomb effect is reduced. As described in the first embodiment, the brightness of the LaB ₆ electron source is 5 × 10
It is about ⁵ A / cm ² str. On the other hand, in the case of a 250 μm square figure drawing shown in FIG. 16, since the mask projection magnification is ４, it is necessary to irradiate the mask with a 1 mm square beam. For this reason, the electron source itself is enlarged to irradiate a large area. For this reason, the luminance is 1 × 10 ² to 1
It is set to about 10 ³ A / cm ² str.

As shown in FIG. 8, a semiconductor integrated circuit 71 includes a memory unit such as a RAM and a ROM, a CPU unit, and a DSP.
Block with a specific function, such as
In some cases, peripheral circuits connecting these components are separately designed. A block having a specific function occupies a relatively large area on a semiconductor integrated circuit. For example, when the size of the semiconductor integrated circuit 71 is 10 to 20 mm square, each functional block has sides of 2 to 5 mm. Also, these functional blocks are often used once the design is completed. If these functional blocks are drawn using a mask of a functional block that is a part of a full chip in a transfer method capable of full-chip drawing as shown in FIG. 16, the overall drawing speed will be improved. At this time, it is necessary to divide these functional block portions from the pattern data. The division criterion may be the area of the collective figure, or a code for specifying the functional block may be embedded in the pattern data at the time of designing the integrated circuit and may be followed according to the code.

As a drawing system, a system shown in FIG. 1 in which three electron beam drawing devices 111, 121 and 131 are combined is used. Apparatus 1
At 21, drawing of a small area collective figure portion and drawing of a large area functional block may be performed using the electron beam drawing apparatus 131 as a transfer type. As described above, in the present embodiment, the transfer method conventionally used for full-chip transfer is partially applied. A full-chip mask cannot be reused despite its high manufacturing cost, but if it is used only in a reusable memory section as in this example, the total mask cost can be reduced and the merit is great. .

Also, depending on the pattern to be drawn, many types of collective figures are required. Usually, the collective figure is selected by electromagnetically deflecting the electron beam. There is an upper limit to the number that can be selected due to the configuration of the system. When a larger number is used, it is necessary to mechanically move the mask for the collective figure. Here, if two electron optical systems for collective graphic drawing are prepared and masks having different shapes of the collective graphic are prepared, the number of selections can be substantially doubled.

FIG. 9 shows a flow of the pattern data dividing process based on the area of the collective figure. First, similarly to the first embodiment, the pattern data is read (step 21), and the drawing condition part is output to the variable shaping pattern data and the batch figure pattern data (step 2).
2). Next, the type of data included in the pattern data portion is determined (step 23), and the variable shaping data is output as variable shaping pattern data (step 24). The collective figure data is determined based on the maximum collectable figure area that can be drawn by each electron optical system as a reference value, and the magnitude relation with this reference value is determined (step 25). Large area batch figure data 2 (step 27)
Is output. At step 28, the presence or absence of remaining data is determined, and the processing from step 23 to step 28 is repeated until all the pattern data has been output.

The pattern data division processing shown in FIG. 9 is based on the area of the pattern. However, the step 15 in FIG. 9 is replaced with the type determination of the collective figure, and two pieces of collective figure data are output for each type. You may.

[Embodiment 3] In the writing method described in Embodiment 1, when pattern data is divided and writing is performed by a plurality of electron beam writing apparatuses, there is a difference in writing time between the apparatuses. There are cases. This greatly depends on the pattern to be drawn, for example, a pattern that occupies a large part of a regular figure increases the percentage of batch figure drawing,
In the case of a pattern having no regularity, drawing by variable shaping is the majority. If there is a difference in the drawing time, the drawing speed is limited to the longer drawing time, which causes waste.

The drawing time is determined by parameters such as the number of shots, current density, sensitivity of the photosensitive agent, beam deflection waiting time, and stage moving time. Therefore, if the contents of the pattern to be drawn are known, the drawing time can be calculated. At this time, for example, if there is a difference of two or more in the writing time, the longer pattern data may be further divided to reduce the difference in the writing time. Further, for example, when there are three electron beam writing apparatuses, the pattern data having the longer writing time may be unconditionally divided to always generate three pattern data.

FIG. 10 shows the flow of the latter example. First,
As in the first embodiment, the pattern data is read (step 31), and the drawing condition part is output to the variable shaped pattern data and the collective figure pattern data (step 32). Next, the type of data included in the pattern data portion is determined (step 33), the variable shaping data is output as variable shaping pattern data (step 34), and the collective figure data is output as collective figure pattern data (step 35). . At step 36, the presence or absence of remaining data is determined, and the processing from step 33 to step 36 is repeated until output of all pattern data is completed. Thus, the pattern data is divided into the variable shaping data and the collective figure data. Thereafter, the writing time of each pattern data is calculated (step 37), and the writing time is determined (step 3).
8). At this time, if the drawing time of the variable shaping pattern data is longer, the variable shaping pattern data is further divided (step 39). If the drawing time of the collective figure pattern data is longer, the collective figure pattern data is further divided (step 40). In this manner, by using the three electron beam writing apparatuses to perform writing, the writing time can be reduced.

[Embodiment 4] In the writing method described in each of the above embodiments, one pattern is divided and writing is performed on one sample by using a plurality of electron beam writing apparatuses.
The accuracy of pattern superposition between a plurality of devices is important. In the superposition by electron beam drawing, it is general that a plurality of mark positions on a sample are detected using an electron beam, and drawing is performed according to the shape. However, when the current density and the beam area of the electron beam are different as in the present invention, there is a possibility that the mark position detection accuracy, which is the basis of the overlay accuracy, differs between the devices.

To eliminate this difference, it is preferable to use mark position detection without using an electron beam. The optimal means from the viewpoint of detection accuracy is optical detection. FIG.
An example is shown in FIG. FIG. 11 shows the objective lens 1207, the sample 1208, and the XY of the electron beam writing apparatus described in FIG.
Only the stage 1209 is shown. FIG. 11 (a)
Is an example of measuring the same place as the electron beam 1202. Light is obliquely incident on the sample from the light source 91, and an image on the sample is detected by the optical mark detection device detector 92 to measure the position. FIG. 11B shows an electron beam 1202.
This is an example of measuring a different place. If the relative position between the optical mark detection device detection 93 and the electron beam 2 is calibrated in advance, the mark position and the drawing position can be converted. At this time, the shape of the mark may be adjusted for electron beam detection or for light detection.

[Fifth Embodiment] As described in the fourth embodiment, when performing overlay drawing, it is general to detect a plurality of mark positions on the sample and draw according to the shape. is there. Increasing the number of marks to be detected improves accuracy, but takes time to detect. Therefore, a method is adopted in which the number of marks to be detected is limited within a range in which required accuracy can be ensured, and an error is diffused according to the position of a pattern to be drawn.

FIG. 12 shows an example in which a plurality of chips 1002 are drawn using a wafer 1001 as a sample.
The minimum required mark position detection is the detection of the wafer alignment mark 1003 outside the pattern area.
If two or more of these marks are detected, a position error and a rotation error when the sample is loaded in the apparatus can be calculated. Drawing may be performed according to the chip arrangement based on this value. In order to perform higher-precision writing, a plurality of chip alignment marks 1004 around the chip can be detected to reduce an XY stage movement error and a chip arrangement error. For example, a method of taking the four corners and the center of the whole chip, or dividing the whole chip into upper and lower parts and performing drawing in units of blocks for every six chips may be used. Further, the mark positions of the four corners may be detected for each chip, and the drawing may be performed in accordance with the detected mark positions.

If the same algorithm as described above is used in each electron beam lithography apparatus, the difference between the overlay errors between the apparatuses can be minimized. However, it is natural that different parameters such as the manner of movement of the XY stage and the distortion shape of the electron beam deflection are separately measured in each apparatus and reflected in the overlay drawing.

[Embodiment 6] A problem peculiar to electron beam writing is the proximity effect. A practical method of correcting the proximity effect at high speed is to calculate the degree of influence in advance according to the density of the pattern to be drawn and change the irradiation amount at the time of drawing. Since the proximity effect is affected by all surrounding patterns, a correct result cannot be obtained if the drawing data is divided as in the present invention and the proximity effect correction calculation is performed thereafter. Therefore, for example, in the system shown in FIG. 1, an irradiation amount correction calculation function for performing proximity effect correction is added to the data dividing device 102 to calculate an area density map. Then, the area density map calculation is performed before or simultaneously with the data division. The divided pattern data and area density map are
After sending to the control devices 112, 122 and 132, drawing is started.

The irradiation amount correction calculation function may be built in the control device of the apparatus. In this case, the data before the division is first sent to, for example, the control device 112 to calculate the area density map. This map is stored in the controller 12
2 and 132, and the pattern data divided by the data dividing device 102 is drawn based on the area density map.

[Embodiment 7] FIG. 13 shows a manufacturing process of a semiconductor integrated circuit using the electron beam drawing method of the present invention. 13A to 13D are cross-sectional views of the element showing the steps. The P well layer 1121, P layer 1122, field oxide film 1123, polycrystalline silicon / silicon oxide film gate 1124, P high concentration diffusion layer 1125, N high concentration diffusion layer 1
126, etc. (FIG. 13A). Next, an insulating film 1127 of phosphorus glass (PSG) is deposited, and the insulating film 112 is formed.
7 was dry-etched to form a contact hole 1128 (FIG. 13B).

Next, the W / TiN electrode wiring 1
130 material is applied, and a photosensitive agent 1129 is applied thereon,
The photosensitive agent 1129 was patterned using the electron beam drawing method of the present invention (FIG. 13C). Then, a W / TiN electrode wiring 1130 was formed by dry etching or the like. Next, an interlayer insulating film 1131 was formed, and a hole pattern 1132 was formed by an ordinary method. The inside of the hole pattern 1132 is filled with a W plug, and the Al second wiring 1 is formed.
133 were ligated (FIG. 13D). The subsequent passivation process used a conventional method.

Although only the main manufacturing steps have been described here, the same steps as in the conventional method were used except that the electron beam drawing method of the present invention was used in the lithography step of forming the W / TiN electrode wiring. Through the above steps, a pattern can be formed without deterioration in quality.
Could be manufactured with a high yield. As a result of manufacturing a semiconductor integrated circuit by using the electron beam writing method of the present invention, the writing speed was improved and the production amount was increased.

[0058]

According to the present invention, it is possible to carry out drawing at an optimum current density by the collective figure system and the variable shaping system, respectively, and the drawing speed can be improved as a whole.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram showing an example of an electron beam writing system according to the present invention.

FIG. 2 is a diagram showing an example of a drawing order in a plurality of electron optical systems.

FIG. 3 is a diagram showing an example of dividing a drawing pattern.

FIG. 4 is a diagram showing a mounting mode of an electron beam writing system.

FIG. 5 is a diagram showing an example of a sample holding device.

FIG. 6 is a diagram showing an example of division of drawing pattern data.

FIG. 7 is a diagram showing a division flow of drawing pattern data.

FIG. 8 illustrates a configuration example of a semiconductor integrated circuit.

FIG. 9 is a diagram showing a flow for dividing pattern data by the area of a collective figure.

FIG. 10 is a diagram showing a flow of re-dividing based on a drawing time of a divided drawing pattern.

FIG. 11 is a diagram showing a configuration example of an optical mark detector.

FIG. 12 is a diagram showing an example of drawing chips and alignment marks on a wafer.

FIG. 13 is a diagram showing a step of forming a semiconductor integrated circuit by the electron beam drawing method of the present invention.

FIG. 14 is a view showing a conventional electron beam drawing apparatus.

FIG. 15 is a diagram showing a collective figure mask;

FIG. 16 is a view showing a conventional transfer type electron beam writing apparatus.

[Explanation of symbols]

101: sample transport device, 102: data dividing device, 10
3: pattern data, 104: drawing procedure control device, 10
5: Drawing time calculation device, 106: Vacuum chamber, 111: Electron beam drawing device 1, 112: Control device, 121: Electron beam drawing device 2, 122: Control device, 131: Electron beam drawing device 3, 132: Control device , 31: writing pattern, 32: collective figure pattern, 33: variable shaping pattern, 41: electron beam writing apparatus 1, 42: electron beam writing apparatus 2, 43: electron beam writing apparatus 3, 44: sample transfer apparatus, 45: Evacuation chamber, 46: sample cassette, 5
1: Sample holding device, 52: Wafer, 53: Glass mask, 61: Pattern data, 62: Drawing condition part, 63:
Pattern data section, 64: variable shaping data section, 65: batch figure data section, 66: variable shaping pattern data, 6
7: collective figure pattern data, 71: semiconductor integrated circuit,
1202: electron beam, 1207: objective lens, 120
8: sample, 1209: XY stage, 91: light source, 9
2: Optical mark detector, 93: Optical mark detector, 1001: Wafer, 1002: Chip, 1003:
Wafer alignment mark, 1004: chip alignment mark, 1120: N minus silicon substrate, 11
21: P well layer, 1122: P layer, 1123: field oxide film, 1124: polycrystalline silicon / silicon oxide film gate, 1125: P high concentration diffusion layer, 1126: N high concentration diffusion layer, 1127: insulating film, 1128 : Contact hole, 1129: photosensitive agent, 1130: W / Ti electrode wiring, 1131: interlayer insulating film, 1132: hole pattern, 1133: aluminum second wiring, 1201: electron gun, 1
202: electron beam, 1203: first mask, 120
4: Selective deflector, 1205: Second mask, 1206: Reduction lens, 1207: Objective lens, 1208: Sample, 1
209: XY stage, 1210: drawing control device, 12
11: mask moving mechanism, 1212: moving mechanism control device,
1213: XY stage controller, 1301: batch figure aperture, 1302: variable shaping aperture, 1401: illumination system, 1402: electron beam, 1403: lens, 140
4: deflector, 1405: mask, 1406: first projection lens, 1407: deflector, 1408: limiting aperture,
1409: second projection lens, 1410: deflector, 141
1: Sample

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Yasunari Hayata 1-280 Higashi-Koigabo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. (72) Inventor Saito ▲ Toku ▼ ro 1-280 Higashi-Koigabo, Kokubunji-shi, Tokyo Stock Central Research Laboratory, Hitachi, Ltd. CC09 CC14 CD13 EA02 FA08

Claims (5)

[Claims] 1. An electron beam writing method for irradiating a sample with an electron beam to write a pattern, wherein the writing is performed on one sample using a plurality of electron optical systems having different luminances. . 2. An electron beam writing method for writing a pattern by irradiating a sample with an electron beam, wherein pattern data for writing is divided into a portion for writing by a variable shaping method and a portion for writing by a collective figure method. Steps, a portion to be drawn by the variable shaping method is drawn by an electron optical system that draws a pattern by a variable shaping method, and a portion to be drawn by the collective figure method is drawn by an electronic optical system that draws a pattern by a collective figure method. An electron beam writing method, wherein the brightness of an electron optical system that performs pattern writing by the variable shaping method is higher than the brightness of an electron optical system that performs pattern writing by the collective figure method. 3. An electron beam writing method for writing a pattern on a sample by using both a variable shaping method and a collective figure method, wherein a pattern data to be drawn is written by a variable figure method and a pattern is drawn by a collective figure method. A step of calculating a drawing time of the divided pattern data; and an electron optical system that performs pattern drawing by a variable shaping method based on the calculated drawing time and pattern drawing by a collective figure method. Adjusting the brightness of the electron optical system to be performed; and performing drawing on one sample by the electron optical system for performing pattern drawing by the variable shaping method and the electron optical system for performing pattern drawing by the collective graphic method. An electron beam drawing method characterized by the above-mentioned. 4. An electron beam drawing system including an electron optical system for performing pattern drawing by a variable shaping method and an electron optical system for performing pattern drawing by a collective figure method, wherein pattern data to be drawn is drawn by a variable shaping method. Pattern dividing means that divides the pattern data into a part for performing drawing in the collective graphic method, a drawing time calculating means for calculating the drawing time of the divided pattern data, and the variable shaping based on the calculated drawing time. Means for adjusting the brightness of the electron optical system for performing pattern drawing in the system and the brightness of the electron optical system for performing pattern drawing in the collective figure system; A sample transport unit for transporting the sample between the electron optical system that performs pattern drawing, and an electron optical system that performs pattern drawing by the variable shaping method; Electron beam drawing system, characterized in that for drawing in a single sample using a serial electron optical system for performing pattern writing in bulk shapes manner. 5. An electron beam lithography system including an electron optical system for performing pattern drawing by a variable shaping method and an electron optical system for performing pattern drawing by a collective figure method, for correcting a proximity effect of pattern data to be drawn. Means for performing the dose correction calculation of the above, pattern dividing means for dividing the pattern data subjected to the dose correction calculation into a portion to be drawn by the variable shaping method and a portion to be drawn by the collective figure method, and the divided pattern A drawing time calculating means for calculating a drawing time of data; a luminance of an electron optical system for performing pattern drawing by the variable shaping method based on the calculated drawing time; and a luminance of an electron optical system for performing pattern drawing by the collective figure method. Means for adjusting the distance between the electron optical system that performs pattern drawing by the variable shaping method and the electron optical system that performs pattern drawing by the collective graphic method A sample transporting means for transporting a material, and drawing by correcting the proximity effect on one sample using an electron optical system for drawing a pattern by the variable molding method and an electron optical system for drawing a pattern by the batch figure method. An electron beam writing system.